CN112408883B

CN112408883B - Concrete pipe pile and preparation method thereof

Info

Publication number: CN112408883B
Application number: CN202011344019.XA
Authority: CN
Inventors: 鱼奇; 李征; 张小平; 杨超
Original assignee: Shaanxi Zhuhengtai Pipe Pile Co ltd
Current assignee: Shaanxi Zhuhengtai Pipe Pile Co ltd
Priority date: 2020-11-25
Filing date: 2020-11-25
Publication date: 2022-03-29
Anticipated expiration: 2040-11-25
Also published as: CN112408883A

Abstract

The application relates to the technical field of concrete pipe piles, and particularly discloses a concrete pipe pile and a preparation method thereof, wherein the concrete pipe pile comprises concrete and reinforcing steel bars, and the concrete is prepared from the following raw materials in parts by weight: cement 300-; 130 portions of quartz powder 110-; 650 portions and 670 portions of sand; 1320 and 1350 parts of stones; 8-10 parts of a high-efficiency water reducing agent; 120 portions of water and 140 portions of water; 15-30 parts of modified mucuna fiber; the modified mucuna fiber is prepared by carrying out alkaline pretreatment on mucuna vine stem fibers and then carrying out esterification reaction with aromatic acid. The concrete pipe pile of this application has the advantage that improves the impervious performance of tubular pile.

Description

Concrete pipe pile and preparation method thereof

Technical Field

The application relates to the technical field of concrete tubular piles, in particular to a concrete tubular pile and a preparation method thereof.

Background

The pipe piles are classified into prestressed concrete pipe piles and prestressed high-strength concrete pipe piles according to the concrete strength grade or effective pre-stress. The code of the prestressed concrete pipe pile is PC, the code of the prestressed high-strength concrete pipe pile is PHC, and the code of the thin-wall pipe pile is PTC. The concrete strength of the PC pile is not lower than C60, the strength grade of the thin-wall pipe pile is not lower than C60, and the concrete strength grade of the PHC pile is not lower than C80. The pipe pile is used as a building component for pile foundation construction, and is widely applied to various engineering structures such as industrial and civil buildings, road and railway bridges, ports and wharfs and the like.

Because certain pores exist in the concrete, the impermeability needs to be considered when the pipe pile is applied underground. Ordinary concrete does not have impervious performance, and the impervious anticorrosive mode of tubular pile among the relevant art does: the surface of the pipe pile is coated with an asphalt coating or a wear-resistant and corrosion-resistant coating, but the coating is easy to fall off due to friction force in the construction process.

In view of the above-mentioned related technologies, the inventor believes that there is a defect that the impermeability of the pipe pile needs to be improved.

Disclosure of Invention

In order to improve the impermeability of the pipe pile, the application provides a concrete pipe pile and a preparation method thereof.

First aspect, this application provides a concrete pipe pile, adopts following technical scheme:

the concrete pipe pile comprises concrete and reinforcing steel bars, wherein the concrete is prepared from the following raw materials in parts by weight:

cement 300-;

130 portions of quartz powder 110-;

650 portions and 670 portions of sand;

1320 and 1350 parts of stones;

8-10 parts of a high-efficiency water reducing agent;

120 portions of water and 140 portions of water;

15-30 parts of modified mucuna fiber;

the modified mucuna fiber is prepared by carrying out alkaline pretreatment on mucuna vine stem fibers and then carrying out esterification reaction with aromatic acid.

By adopting the technical scheme, the modified elaeagnus mollis fiber prepared by alkaline pretreatment and esterification reaction of aromatic acid can promote low molecular impurities such as lignin, pectin and hemicellulose to be separated from the elaeagnus mollis fiber during the alkaline pretreatment, so that the mechanical property and high temperature resistance of the elaeagnus mollis fiber are enhanced, the elaeagnus mollis fiber is subjected to esterification reaction with the aromatic acid after the alkaline pretreatment and esterification grafting treatment of the aromatic acid, the dispersibility of the elaeagnus mollis fiber is enhanced, and the temperature resistance of the elaeagnus mollis fiber can be enhanced, so that the elaeagnus mollis fiber can not be damaged in the high-temperature steam curing process of the tubular pile, the modified elaeagnus mollis fiber can improve the connectivity of a micropore structure in concrete, improve the impermeability of the concrete, form a three-dimensional network structure in the concrete, and play a role in inhibiting the generation of cracks during and after the curing of the concrete, and the anti-permeability performance of the concrete is enhanced.

Optionally, the preparation method of the modified mucuna fiber comprises the following steps: taking 15-30 parts of vine stems from mucuna hemp stems, washing with water, drying and crushing to obtain crude fibers; adding 0.5-1.5 parts of sodium hydroxide and 0.1-0.2 part of surfactant into 60-80 parts of water, and uniformly mixing to obtain a treatment solution; putting the crude fiber into the treatment solution, heating to 60-80 ℃, reacting for 30-40min, filtering, washing with water, and drying to obtain pretreated fiber; uniformly mixing the pretreated fiber, 2-4 parts of aromatic acid, 0.1-0.3 part of esterification catalyst and 100-120 parts of ethanol, heating to 90-100 ℃, reacting for 10-15min, filtering, washing and drying to obtain the modified mucuna fiber.

By adopting the technical scheme, the surfactant can promote the crude fiber to be separated in water, so that the reaction of the crude fiber and sodium hydroxide is facilitated, the separation of impurities can be promoted, and the subsequent grafting reaction with aromatic acid is facilitated, so that the modified mucuna fiber is obtained, and the impermeability of concrete is enhanced.

Optionally, the surfactant is selected from any one of sodium lignosulfonate, sodium dodecylbenzenesulfonate and sodium dibutylnaphthalenesulfonate.

By adopting the technical scheme, the surfactant has good stability, can promote the dispersion of crude fibers and is beneficial to removing impurities.

Optionally, the aromatic acid is selected from any one of terephthalic acid, isophthalic acid and phthalic acid.

By adopting the technical scheme, the aromatic acid structure is provided with the high-temperature-resistant benzene ring, and the pretreated fiber can be more easily subjected to esterification reaction with the binary aromatic acid, so that the dispersity of the mucuna fiber in concrete is enhanced, the temperature resistance of the mucuna fiber can be enhanced, and the impermeability of the concrete is improved.

Optionally, the esterification catalyst is selected from any one of sodium hypophosphite, disodium hydrogen phosphate and sodium phosphate.

By adopting the technical scheme, the catalyst can promote the pretreated fiber and the aromatic acid to fully perform esterification grafting reaction.

Optionally, the length of the coarse fibers is 5-20 mm, and the fineness of the coarse fibers is 0.5-5D.

By adopting the technical scheme, the length and fineness of the coarse fibers are controlled, so that the coarse fibers are favorably and uniformly dispersed in the concrete to form a net structure, the connectivity of a microporous structure in the concrete is improved, and the impermeability of the concrete is enhanced.

Optionally, the pretreated fiber is subjected to a heat treatment step before esterification: and (3) placing the pretreated fiber in an inert gas protective atmosphere, and carrying out heat preservation treatment at the temperature of 160-170 ℃ for 5-10 min.

By adopting the technical scheme, the inside of the pretreated fiber contains crystal water, which can influence the esterification grafting of the pretreated fiber, and the heat treatment step can reduce the crystallinity of the pretreated fiber, thereby being beneficial to the esterification grafting reaction and enhancing the impermeability of concrete.

In a second aspect, the present application provides a method for preparing a concrete pipe pile, which adopts the following technical scheme:

a preparation method of a concrete pipe pile comprises the following steps:

mixing cement, quartz powder, sand, stones, a high-efficiency water reducing agent and modified mucuna fiber with water, and uniformly stirring to obtain concrete;

step two, injecting the concrete into a mould, centrifugally forming, maintaining for 5-6 hours at a constant temperature of 80-90 ℃, and cooling to normal temperature;

step three, demolding after curing to obtain a tubular pile blank;

and step four, performing high-pressure steam curing on the pipe pile blank, wherein the steam pressure is 0.9-1.1Mpa, the temperature is 200-210 ℃, and the curing is performed for 5-7 hours to obtain the concrete pipe pile.

By adopting the technical scheme, because the modified hemp fiber is added into the concrete, the temperature resistance of the modified hemp fiber is improved, so that the modified hemp fiber can not be damaged in the high-temperature steam curing process of the tubular pile, the modified hemp fiber can improve the connectivity of a microporous structure in the concrete, and a three-dimensional network structure is formed in the concrete, so that the effect of inhibiting cracks from being generated is achieved during and after the concrete is cured, and the impermeability of the concrete is enhanced.

In summary, the present application has the following beneficial effects:

1. because the modified hemp fiber is adopted, the temperature resistance of the modified hemp fiber is improved, so that the modified hemp fiber can not be damaged in the high-temperature steam curing process of the tubular pile, the modified hemp fiber can improve the connectivity of a microporous structure in concrete, a three-dimensional network structure is formed in the concrete, the effect of inhibiting cracks is achieved when and after the concrete is cured, and the impermeability of the concrete is enhanced.

2. In the application, the heat treatment is preferably carried out before the esterification reaction of the pretreated fibers, and the heat treatment step can reduce the crystallinity of the pretreated fibers, is favorable for the esterification grafting reaction and enhances the impermeability of concrete.

Detailed Description

The present application will be described in further detail with reference to examples.

Preparation example of modified Sesamum indicum fiber

Preparation example 1

The preparation method of the modified mucuna fiber comprises the following steps: taking 15kg of vine from mucuna hemp, washing with water, drying, and crushing to obtain coarse fibers, wherein the length of the coarse fibers is 5mm, and the fineness of the coarse fibers is 0.5D; adding 0.5kg of sodium hydroxide and 0.1kg of surfactant into 60kg of water, wherein the surfactant is sodium lignosulfonate, and uniformly mixing to obtain a treatment solution; putting the crude fiber into the treatment solution, heating to 60 ℃, reacting for 40min, filtering, washing with water, and drying to obtain pretreated fiber; uniformly mixing the pretreated fiber, 2kg of aromatic acid, 0.1kg of esterification catalyst and 90kg of ethanol, wherein the aromatic acid is terephthalic acid, the esterification catalyst is sodium hypophosphite, heating to 90 ℃, reacting for 15min, filtering, washing and drying to obtain the modified mucuna fiber.

Preparation example 2

The preparation method of the modified mucuna fiber comprises the following steps: taking 20kg of vine from mucuna hemp, washing with water, drying, and crushing to obtain coarse fibers, wherein the length of the coarse fibers is 10mm, and the fineness of the coarse fibers is 3D; adding 1kg of sodium hydroxide and 0.15kg of surfactant into 70kg of water, wherein the surfactant is sodium dodecyl benzene sulfonate, and uniformly mixing to obtain a treatment solution; putting the crude fiber into the treatment solution, heating to 70 ℃ for reaction for 35min, filtering, washing with water, and drying to obtain pretreated fiber; uniformly mixing the pretreated fiber, 3kg of aromatic acid, 0.2kg of esterification catalyst and 95kg of ethanol, wherein the aromatic acid is isophthalic acid, the esterification catalyst is disodium hydrogen phosphate, heating to 95 ℃, reacting for 12min, filtering, washing and drying to obtain the modified mucuna fiber.

Preparation example 3

The preparation method of the modified mucuna fiber comprises the following steps: taking 30kg of vine from mucuna hemp, washing with water, drying, and crushing to obtain coarse fibers, wherein the length of the coarse fibers is 20mm, and the fineness of the coarse fibers is 5D; adding 1.5kg of sodium hydroxide and 0.2kg of surfactant into 80kg of water, wherein the surfactant is sodium dibutylnaphthalenesulfonate, and uniformly mixing to obtain a treatment solution; putting the crude fiber into the treatment solution, heating to 80 ℃, reacting for 30min, filtering, washing with water, and drying to obtain pretreated fiber; uniformly mixing the pretreated fiber, 4kg of aromatic acid, 0.3kg of esterification catalyst and 100kg of ethanol, wherein the aromatic acid is phthalic acid, the esterification catalyst is sodium phosphate, heating to 100 ℃, reacting for 10min, filtering, washing with water, and drying to obtain the modified mucuna fiber.

Preparation example 4

The modified mucuna fiber is different from example 1 in that a surfactant is not added in the preparation method.

Preparation example 5

The modified Sesamum indicum fiber was different from example 1 in that the weight of the surfactant in the preparation method was 0.05 kg.

Preparation example 6

The modified mucuna fiber is different from example 1 in that the aromatic acid is phenylacetic acid.

Preparation example 7

The modified mucuna fiber is different from example 1 in that the esterification catalyst in the preparation method is ferric sulfate.

Preparation example 8

The modified Sesamum indicum fiber was different from example 1 in that the length of the crude fiber in the preparation method was 2 mm.

Preparation example 9

The modified Sesamum indicum fiber was different from example 1 in that the length of the crude fiber in the preparation method was 30 mm.

Preparation example 10

The modified mucuna fiber is different from the modified mucuna fiber in example 1 in that the pretreated fiber is subjected to a heat treatment step before the esterification reaction: and (3) placing the pretreated fiber in a nitrogen protection atmosphere, and carrying out heat preservation treatment at 160 ℃ for 10 min.

Preparation example 11

The modified mucuna fiber is different from the modified mucuna fiber in example 1 in that the pretreated fiber is subjected to a heat treatment step before the esterification reaction: and (3) placing the pretreated fiber in an inert gas protection atmosphere, and carrying out heat preservation treatment at the temperature of 170 ℃ for 5 min.

Comparative preparation example 1

The preparation method of the crude fiber of the mucuna hemp comprises the following steps: taking 15kg of vine stem from Mucuna birdwoodiana, washing with water, drying, and pulverizing to obtain crude fiber with length of 5mm and fineness of 0.5D.

Comparative preparation example 2

The preparation method of the modified mucuna fiber comprises the following steps: taking 15kg of vine from mucuna hemp, washing with water, drying, and crushing to obtain coarse fibers, wherein the length of the coarse fibers is 5mm, and the fineness of the coarse fibers is 0.5D; adding 0.5kg of sodium hydroxide and 0.1kg of surfactant into 60kg of water, wherein the surfactant is sodium lignosulfonate, and uniformly mixing to obtain a treatment solution; and (3) putting the crude fiber into the treatment solution, heating to 60 ℃, reacting for 40min, filtering, washing with water, and drying to obtain the modified mucuna fiber.

Comparative preparation example 3

The preparation method of the modified mucuna fiber comprises the following steps: taking 15kg of vine from mucuna hemp, washing with water, drying, and crushing to obtain coarse fibers, wherein the length of the coarse fibers is 5mm, and the fineness of the coarse fibers is 0.5D; uniformly mixing the crude fiber, 2kg of aromatic acid, 0.1kg of esterification catalyst and 90kg of ethanol, wherein the aromatic acid is terephthalic acid, the esterification catalyst is sodium hypophosphite, heating to 90 ℃, reacting for 15min, filtering, washing and drying to obtain the modified mucuna fiber.

Examples

Example 1

A concrete pipe pile comprises concrete and reinforcing steel bars, wherein the concrete is prepared from the raw materials shown in Table 1, modified Mucuna birdwoodiana fiber is prepared from preparation example 1, quartz powder and sand are fine aggregates, stone is coarse aggregate, and a high-efficiency water reducing agent is a polycarboxylic acid water reducing agent and is purchased from Jinan province chemical engineering and science Limited company.

The preparation method of the concrete pipe pile comprises the following steps:

step two, injecting the concrete into a mould, centrifugally forming, maintaining for 6 hours at a constant temperature of 80 ℃, and cooling to normal temperature;

step three, demolding after curing to obtain a tubular pile blank;

and step four, curing the pipe pile blank by high-pressure steam at the steam pressure of 0.9Mpa and the temperature of 200 ℃ for 7 hours to obtain the concrete pipe pile.

Example 2

A concrete pipe pile, which is different from example 1 in that concrete is prepared from the raw materials shown in table 1, wherein modified fibrilia sessiliflorum is prepared from preparation example 2.

Example 3

A concrete pipe pile, which is different from example 1 in that concrete is prepared from the raw materials shown in table 1, wherein modified fibrilia sessiliflorum is prepared from preparation example 3.

Table 1 materials and weights (kg) of concrete pipe piles in examples 1 to 3

Raw materials	Example 1	Example 2	Example 3
				Cement	300	310	320
Quartz powder	110	120	130
				Sand	670	660	650
Stone	1320	1330	1350
				High-efficiency water reducing agent	8	9	10
Water (W)	120	130	140
				Modified fibrilia of Sesamum indicum	15	20	30

Examples 4 to 9

A concrete pipe pile, which is different from the concrete pipe pile in example 1 in that modified fibrilia sessiliflorum in concrete raw materials are prepared in preparation examples 4 to 9 respectively.

Example 10

The embodiment 1 is different in that the preparation method of the concrete pipe pile comprises the following steps:

step two, injecting the concrete into a mould, centrifugally forming, maintaining for 5 hours at a constant temperature of 90 ℃, and cooling to normal temperature;

step three, demolding after curing to obtain a tubular pile blank;

and step four, curing the pipe pile blank by high-pressure steam at the steam pressure of 1.1Mpa and the temperature of 210 ℃ for 5 hours to obtain the concrete pipe pile.

Examples 11 to 12

A concrete pipe pile, which is different from the concrete pipe pile in example 1 in that modified fibrilia sessiliflorum in a concrete raw material is prepared in preparation examples 10 to 11 respectively.

Comparative example

Comparative example 1

A concrete pipe pile, which is different from the concrete pipe pile in example 1 in that modified mucuna fiber is not added.

Comparative example 2

A concrete pipe pile, which is different from the concrete pipe pile in example 1 in that modified mucuna fiber is replaced by equal weight of crude mucuna fiber prepared in comparative preparation example 1.

Comparative example 3

A concrete pipe pile, which is different from example 1 in that modified mucuna fiber was prepared from comparative preparation example 2.

Comparative example 4

A concrete pipe pile, which is different from example 1 in that modified mucuna fiber was prepared from comparative preparation example 3.

Performance test

Test method

(1) Referring to a concrete water permeability resistance test method specified in GB/T50082-2009 test method Standard for testing Long-term Performance and durability of ordinary concrete, the concrete in examples 1-12 and comparative examples 1-4 is made into a standard test block, the water seepage height under the constant water pressure of 0.8MPa is tested, 6 groups of tests are repeated, and the average water seepage height (mm) is calculated.

(2) Thermogravimetric analysis: the test was carried out using a thermal analyzer with a gas flow of 10mL/min, a temperature rise rate of 5 ℃/min, and a temperature range of 30-500 ℃ and the 5% weight loss temperature (T5) for preparations 1-9 and comparative preparation was determined according to the TGA curve.

In addition, the concrete pipe pile in the embodiment of the application is tested, and the appearance quality, the size deviation, the bending resistance and the concrete compressive strength all meet the requirements of the standard GB13476-2009 pretensioned prestressed concrete pipe pile.

TABLE 2 results of Water permeability resistance test

Example/comparative example numbering	Average water penetration height/mm
		Example 1	12.0
Example 2	11.5
		Example 3	10.8
Example 4	15.1
		Example 5	14.2
Example 6	13.5
		Example 7	15.7
Example 8	12.9
		Example 9	14.2
Example 10	12.2
		Example 11	9.5
Example 12	9.3
		Comparative example 1	40.5
Comparative example 2	35.6
		Comparative example 3	32.8
Comparative example 4	31.2

TABLE 3 results of thermogravimetric tests

Combining examples 1-12 and comparative examples 1-4 and combining table 2, it can be seen that the average water penetration height of comparative example 1 is as high as 40.5mm, which indicates that the concrete of comparative example 1 has poor water impermeability, and that the average water penetration height of comparative example 2 is reduced to 35.6mm by adding the elaeagnus mollis fiber without modification on the basis of comparative example 1, which indicates that although the water impermeability of the concrete can be improved, the water impermeability still needs to be improved when the concrete is added without modification; comparative example 3 the alkali modification treatment was performed on the mucuna fiber based on comparative example 2, and the average water penetration height was further reduced to 32.8mm, which indicates that the alkali modification treatment of the mucuna fiber can further improve the water impermeability of concrete, probably because the alkali modification treatment improves the interface compatibility between the mucuna fiber and the concrete; comparative example 4 the esterification graft reaction was performed on the mucuna fiber based on comparative example 2, and the average water penetration height was further reduced to 31.2mm, which indicates that the water penetration resistance of the concrete could be further improved by the esterification graft reaction of the mucuna fiber, because the dispersibility of the mucuna fiber is enhanced, the water penetration resistance of the concrete is improved, the temperature resistance of the mucuna fiber can be improved due to the benzene ring contained in the aromatic acid, and the structure of the modified mucuna fiber is not damaged when the high pressure steam curing is performed.

Example 1 after the alkali modification and the esterification grafting are carried out on the mucuna fiber on the basis of the comparative example 2, the average water seepage height is greatly reduced to 12mm, and the reduction range is larger than the sum of the reduction ranges of the comparative examples 3 and 4, which shows that the alkali modification and the esterification grafting can be synergistic, and the water impermeability of the concrete is obviously improved; example 4 the average water penetration height rises to 15.1mm without the addition of surfactant, indicating that the addition of surfactant can improve the water impermeability of concrete, probably because the surfactant promotes the separation of impurities during alkali modification; example 5 when the surfactant was added below the minimum level of the present application, the average water penetration height rose to 14.2mm, indicating that it was difficult to improve the water impermeability of the concrete when too little surfactant was added; example 6 shows that the average water penetration height is increased to 13.5mm when aromatic acid is replaced by phenylacetic acid, and the water impermeability is inferior to example 1, which indicates that the modification of the fibrilia sessiliflorum by using dicarboxylic acid, isophthalic acid and phthalic acid is better than the modification of the phenylacetic acid, example 7 shows that the average water penetration height is increased to 15.7mm when an esterification catalyst is replaced by ferric sulfate, which indicates that the modification of the fibrilia sessiliflorum by using sodium hypophosphite, disodium hydrogen phosphate and sodium phosphate as catalysts is better than the modification of the ferric sulfate, the average water penetration height is increased to 12.9mm when the length of the fibrilia sessiliflorum in example 8 is 2mm, and the average water penetration height is increased to 14.2mm when the length of the fibrilia sessiliflorum in example 9 is 30mm, which indicates that the water impermeability of concrete is affected by the length of the fibrilia sessiliflorum.

The average water penetration heights of the pretreated fibers of examples 11-12 were reduced to 9.5mm and 9.3mm after the heat treatment step before the esterification reaction, indicating that the heat treatment step can improve the water impermeability of concrete, probably because the heat treatment step can reduce the crystallinity of the pretreated fibers, facilitate the combination of the pretreated fibers with aromatic acid, and enhance the water impermeability of concrete.

It can be seen from the combination of the preparation examples 1 to 11 and the comparative preparation examples 1 to 3 and the combination of table 3 that the 5% thermal weight loss temperature of the crude mucuna fiber in the comparative preparation example 1 is 190 ℃ and is difficult to resist the high temperature during the high temperature steam curing, the 5% thermal weight loss temperature of the crude mucuna fiber in the comparative preparation example 2 is raised to 195 ℃ after the crude mucuna fiber is subjected to the alkali treatment, which indicates that the heat resistance stability of the crude mucuna fiber can be improved by the alkali treatment, but the minimum temperature of the tubular pile during the high temperature steam curing is not reached, and the 5% thermal weight loss temperature of the crude mucuna fiber in the comparative preparation example 3 is greatly raised to 220 ℃ after the crude mucuna fiber is subjected to the aromatic acid grafting treatment, which indicates that the heat resistance stability of the crude mucuna fiber can be remarkably improved by the aromatic acid grafting on the mucuna fiber. In preparation example 1, after the alkali treatment and the esterification grafting treatment are carried out simultaneously, the 5% thermal weight loss temperature is further raised to 230 ℃, which indicates that the alkali treatment and the esterification grafting can be synergistic and the heat resistance stability of the modified mucuna fiber is remarkably improved.

Preparation examples 10 to 11 after the pretreated fibers were subjected to heat treatment before the esterification reaction, the 5% thermogravimetric temperature was raised to 233 ℃ and 235 ℃, indicating that the heat treatment step can improve the heat resistance stability of the modified mucuna fiber.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims

1. The concrete pipe pile comprises concrete and reinforcing steel bars, and is characterized in that the concrete is prepared from the following raw materials in parts by weight:

cement 300-;

130 portions of quartz powder 110-;

650 portions and 670 portions of sand;

1320 and 1350 parts of stones;

8-10 parts of a high-efficiency water reducing agent;

120 portions of water and 140 portions of water;

15-30 parts of modified mucuna fiber;

the modified mucuna fiber is prepared by carrying out alkaline pretreatment on mucuna vine stem fibers and then carrying out esterification reaction with aromatic acid, and the preparation method of the modified mucuna fiber comprises the following steps: taking 15-30 parts of vine stems from mucuna hemp stems, washing with water, drying and crushing to obtain crude fibers; adding 0.5-1.5 parts of sodium hydroxide and 0.1-0.2 part of surfactant into 60-80 parts of water, and uniformly mixing to obtain a treatment solution; putting the crude fiber into the treatment solution, heating to 60-80 ℃, reacting for 30-40min, filtering, washing with water, and drying to obtain pretreated fiber; uniformly mixing the pretreated fiber, 2-4 parts of aromatic acid, 0.1-0.3 part of esterification catalyst and 100-120 parts of ethanol, heating to 90-100 ℃, reacting for 10-15min, filtering, washing and drying to obtain the modified mucuna fiber.

2. The concrete pipe pile of claim 1, wherein: the surfactant is selected from any one of sodium lignosulfonate, sodium dodecyl benzene sulfonate and sodium dibutyl naphthalene sulfonate.

3. The concrete pipe pile of claim 1, wherein: the aromatic acid is selected from any one of terephthalic acid, isophthalic acid and phthalic acid.

4. The concrete pipe pile of claim 1, wherein: the esterification catalyst is selected from any one of sodium hypophosphite, disodium hydrogen phosphate and sodium phosphate.

5. The concrete pipe pile of claim 1, wherein: the length of the coarse fiber is 5-20 mm, and the fineness of the coarse fiber is 0.5-5D.

6. The concrete pipe pile of claim 1, wherein: the pretreated fiber is subjected to a heat treatment step before esterification: and (3) placing the pretreated fiber in an inert gas protective atmosphere, and carrying out heat preservation treatment at the temperature of 160-170 ℃ for 5-10 min.

7. The method for preparing a concrete pipe pile according to any one of claims 1 to 6, which is characterized in that: the method comprises the following steps:

step three, demolding after curing to obtain a tubular pile blank;